Adds a Swift Package Manager package that exposes the same board textures, piece images, and theme colour data that the Dart side already ships — so iOS/macOS native targets (e.g. WidgetKit extensions) can consume them without a copy script.

What's included

Package.swift — SPM manifest at the repo root. Declares a single ChessgroundAssets library targeting iOS 16+ / macOS 13+.

swift/Sources/ChessgroundAssets/

• ChessgroundAssets.swift — exposes ChessgroundAssets.bundle for loading assets: Image("board_wood2", bundle: ChessgroundAssets.bundle)
• ChessboardTheme.swift — public ChessboardTheme struct that maps Dart theme names to light/dark square colours, last-move highlight colour, board image name, and piece set. Mirrors the ChessboardColorScheme constants in board_color_scheme.dart.
• Assets.xcassets/ — generated Xcode asset catalog: 21 board texture imagesets and 468 piece imagesets (39 sets × 12 pieces, each with 1x/2x/3x).

scripts/gen-swift-xcassets.sh — regenerates the asset catalog from assets/ whenever boards or piece sets change. No Flutter tooling needed — reads directly from the repo. Run it and commit the result before cutting a new release tag.

.gitignore — added .build/ and .swiftpm/ (SPM artifacts generated at the repo root).

README.md — new "Swift Package (iOS/macOS)" section documenting the dependency, asset naming conventions, ChessboardTheme API, and how to maintain the xcassets.

Motivation

The lichess mobile app's WidgetKit extension previously copied assets out of the pub cache via a shell script, creating a fragile coupling between the iOS build and Flutter tooling. With this package, the extension declares a normal SPM dependency on this repo — assets are versioned alongside the Dart package and consumers just update the SPM version tag when chessground is upgraded.

Asset naming

name matches the ChessboardColorScheme Dart constant. set is the camelCase PieceSet enum .name value. The mono piece set is excluded (non-standard file layout).